Cisco IPS-4255-K9 Installation Guide - Page 394

Glossary trap Trojan engine trunk trusted certificate trusted key tune Message sent by an SNMP agent to an NMS, a console, or a terminal to indicate the occurrence of a significant event, such as a specifically defined condition or a threshold that was reached. Analyzes traffic from nonstandard protocols, such as BO2K and TFN2K. Physical and logical connection between two switches across which network traffic travels. A backbone is composed of a number of trunks. Certificate upon which a certificate user relies as being valid without the need for validation testing; especially a public-key certificate that is used to provide the first public key in a certification path. Public key upon which a user relies; especially a public key that can be used as the first public key in a certification path. Adjusting signature parameters to modify an existing signature. U UDI Unique Device Identifier. Provides a unique identity for every Cisco product. The UDI is composed of the PID, VID, and SN. The UDI is stored in the Cisco IPS ID PROM. UDLD UniDirectional Link Detection. Cisco proprietary protocol that allows devices connected through fiber-optic or copper Ethernet cables connected to LAN ports to monitor the physical configuration of the cables and detect when a unidirectional link exists. When a unidirectional link is detected, UDLD shuts down the affected LAN port and sends an alert, since unidirectional links can cause a variety of problems, such as, spanning tree topology loops. UDP User Datagram Protocol. Connectionless transport layer protocol in the TCP/IP protocol stack. UDP is a simple protocol that exchanges datagrams without acknowledgments or guaranteed delivery, requiring that error processing and retransmission be handled by other protocols. UDP is defined in RFC 768. unblock To direct a router to remove a previously applied block. UniDirectional Link See UDLD. Detection unvirtualized sensing interface An unvirtualized sensing interface has not been divided into subinterfaces and the entire interfaces can be associated with at most one virtual sensor. UPS Uninterruptable Power Source. UTC Coordinated Universal Time. Time zone at zero degrees longitude. Formerly called Greenwich Mean Time (GMT) and Zulu time. V VACL VLAN ACL. An ACL that filters all packets (both within a VLAN and between VLANs) that pass through a switch. Also known as security ACLs. GL-22 Cisco Intrusion Prevention System Appliance and Module Installation Guide for IPS 7.0 OL-18504-01